Abstract The conventional constitutive models employed to describe rock mass creep behaviour associated with the squeezing mechanism are widely adopted in research and design practice. However, these models fail to explicitly replicate the 3-phase creep behaviour especially the accelerated creep phase; only the transient and steady-state creep phase are described explicitly. Hence, this paper presents a viscoelastic viscoplastic with isotropic damage (EVPD) constitutive model that describes the 3-phase behaviour explicitly. This is achieved by the Newtonian dashpot replacement with the fractal-order spring-pot that incorporates isotropic damage effect. Derivation of the fractal-order derivative-based creep constitutive equations is conducted using scaling transformations. The model is then calibrated using experimental data and its derived constitutive equation is implemented in FLAC3D using object-oriented C++. Furthermore, its numerical implementation is employed to simulate delayed response of a tunnel excavated in squeezing ground. The average radii of yield zone around the tunnel estimated by the CVISC and EVPD constitutive models are approximately 8.7 m and 14.7 m, respectively. Whereas the deformation is approximately 29% and accounts for 8% more than the CVISC estimation, the disparity attributed to time-dependent behaviour. It is observed that the EVPD constitutive model describes the creep mechanism and mean deformation in squeezing ground reasonably well.

中文翻译：

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挤压地层隧道时变行为的各向同性损伤本构模型

摘要 用于描述与挤压机制相关的岩体蠕变行为的常规本构模型在研究和设计实践中被广泛采用。然而，这些模型未能明确复制三相蠕变行为，尤其是加速蠕变阶段；仅明确描述了瞬态和稳态蠕变阶段。因此，本文提出了一种具有各向同性损伤的粘弹性粘塑性 (EVPD) 本构模型，该模型明确地描述了三相行为。这是通过用包含各向同性损伤效应的分形阶弹簧罐替换牛顿缓冲器来实现的。使用缩放变换进行基于分形阶导数的蠕变本构方程的推导。然后使用实验数据校准模型，并使用面向对象的 C++ 在 FLAC3D 中实现其导出的本构方程。此外，它的数值实现被用来模拟在挤压地基中开挖的隧道的延迟响应。CVISC 和 EVPD 本构模型估计的隧道周围屈服区的平均半径分别约为 8.7 m 和 14.7 m。虽然变形约为 29%，比 CVISC 估计多 8%，但差异归因于时间相关行为。据观察，EVPD 本构模型很好地描述了挤压地基中的蠕变机制和平均变形。其数值实现用于模拟在挤压地基中开挖的隧道的延迟响应。CVISC 和 EVPD 本构模型估计的隧道周围屈服区的平均半径分别约为 8.7 m 和 14.7 m。虽然变形约为 29%，比 CVISC 估计多 8%，但差异归因于时间相关行为。据观察，EVPD 本构模型很好地描述了挤压地层中的蠕变机制和平均变形。其数值实现用于模拟在挤压地基中开挖的隧道的延迟响应。CVISC 和 EVPD 本构模型估计的隧道周围屈服区的平均半径分别约为 8.7 m 和 14.7 m。虽然变形约为 29%，比 CVISC 估计多 8%，但差异归因于时间相关行为。据观察，EVPD 本构模型很好地描述了挤压地层中的蠕变机制和平均变形。归因于时间依赖行为的差异。据观察，EVPD 本构模型很好地描述了挤压地基中的蠕变机制和平均变形。归因于时间依赖行为的差异。据观察，EVPD 本构模型很好地描述了挤压地基中的蠕变机制和平均变形。